An apparatus and method for joining two synthetic resin members through vibration welding have been well known. FIG. 2 shows an example a of a conventional vibration welding apparatus.
A fixed jig part d and a movable jig part e, which constitute a fixed-side jig c, are disposed on a base b. The movable jig part e is slidably supported on a slide rail f so as to be movable towards or away from the fixed jig part d. The movable jig part e is moved toward or away from the fixed jig part d by a cylinder g mounted on the base b.
A vibrating member h, which is supported so as to be vibrated by a vibration generating mechanism i, supports a fixed jig part k and a movable jig part l, which together constitute a jig j on the side of the vibrating mechanism. The movable jig part l is slidably supported on a slide rail m so as to be movable towards or away from the fixed jig part k. The movable jig part l is moved toward or away from the fixed jig part k by a cylinder n mounted on the vibrating member h.
For example, to join two lens members o, p by vibration welding, the lens member o is first temporarily fixed to the movable jig part e, and then the cylinder g is then driven to move the movable jig part e towards the fixed jig part d such that the lens member o is fixed between the movable jig part e and the fixed jig part d. Then, the lens member p is temporarily fixed to the movable jig part l, and the cylinder n is driven to move the movable jig part l toward the fixed jig part k such that the lens member p is fixed between the movable jig part l and the fixed jig part k.
A cylinder (not shown) is driven to move the base b upward such that welding portions o', p' of the respective lens members o, p are brought into pressure contact with each other. The vibration generating mechanism i is then activated to vibrationally drive the vibrating member h so as to weld together the welding portions o' and p' of the lens members o, p.
In the conventional vibration welding apparatus a as described above, the vibrating member h carries all elements required for holding one of the synthetic resin members, that is, in the aforementioned example, the lens member p, including the fixed jig part k, movable jig part l, slide rail m for supporting the movable jig l, cylinder n for moving the movable jig l, and the like. As a result, the weight of the overall vibrating member is high, requiring a large vibration generating mechanism. Welding of a large synthetic resin member requires a large jig, thus further increasing the weight of the vibrating member. In this case, it becomes difficult to vibrationally drive the vibrating member.
In conjunction with the foregoing problem, it is an object of the present invention to reduce the weight of the vibrating member and to make vibration welding of large synthetic resin members possible.